System and method for powering or charging receivers or devices having small surface areas or volumes

ABSTRACT

Systems and methods for enabling transfer of power, from a wireless charger or power supply, to one or more receivers placed on or near the wireless charger or power supply, including powering or charging one or multiple receivers or devices having small surface areas or volumes. In accordance with an embodiment, a receiver coil can be generally shaped as a blade or thin solenoid, which receives power inductively, which is then used to power or charge one or more electronic devices. Applications include inductive or magnetic charging and power, and particularly usage in mobile, electronic, electric, lighting, or other devices, batteries, power tools, kitchen, industrial, medical or dental, or military applications, vehicles, robots, trains, and other usages.

CLAIM OF PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalPatent Application No. 61/811,638, titled “SYSTEM AND METHOD FORPOWERING OR CHARGING ONE OR MULTIPLE RECEIVERS OR DEVICES HAVING SMALLSURFACE AREAS OR VOLUMES” filed Apr. 12, 2013; and is related to U.S.Patent Publication No. 20130285604 (U.S. patent application Ser. No.13/828,789), titled “SYSTEMS AND METHODS FOR WIRELESS POWER TRANSFER”filed Mar. 14, 2013; and U.S. Patent Publication No. 20120235636 (U.S.patent application Ser. No. 13/352,096), titled “SYSTEMS AND METHODS FORPROVIDING POSITIONING FREEDOM, AND SUPPORT OF DIFFERENT VOLTAGES,PROTOCOLS, AND POWER LEVELS IN A WIRELESS POWER SYSTEM”, filed Jan. 17,2012, which claims the benefit of priority to U.S. Provisional PatentApplication No. 61/433,883, titled “SYSTEM AND METHOD FOR MODULATING THEPHASE AND AMPLITUDE OF AN ELECTROMAGNETIC WAVE IN MULTIPLE DIMENSIONS”,filed Jan. 18, 2011; U.S. Provisional Patent Application No. 61/478,020,titled “SYSTEM AND METHOD FOR MODULATING THE PHASE AND AMPLITUDE OF ANELECTROMAGNETIC WAVE IN MULTIPLE DIMENSIONS”, filed Apr. 21, 2011; andU.S. Provisional Patent Application No. 61/546,316, titled “SYSTEMS ANDMETHODS FOR PROVIDING POSITIONING FREEDOM, AND SUPPORT OF DIFFERENTVOLTAGES, PROTOCOLS, AND POWER LEVELS IN A WIRELESS POWER SYSTEM”, filedOct. 12, 2011; each of which above applications are herein incorporatedby reference.

COPYRIGHT NOTICE

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FIELD OF INVENTION

Embodiments of the invention are generally related to systems andmethods for enabling transfer of power, from a wireless charger or powersupply, to one or more receivers placed on or near the wireless chargeror power supply, including powering or charging one or multiplereceivers or devices having small surface areas or volumes.

BACKGROUND

Wireless technologies for powering and charging mobile and otherelectronic or electric devices, batteries and vehicles have beendeveloped. Such systems generally use a wireless power charger ortransmitter, in combination with a wireless power receiver, to provide ameans for transfer of power. In some systems, the charger and receivercoil parts of the system are aligned and of comparable size. However, insome applications, it would be preferable to use receiver coils orantennas that have smaller areas or volumes. These are the general areasthat embodiments of the invention are intended to address.

SUMMARY

Described herein are systems and methods for enabling transfer of power,from a wireless charger or power supply, to one or more receivers placedon or near the wireless charger or power supply, including powering orcharging one or multiple receivers or devices having small surface areasor volumes. In accordance with an embodiment, a receiver coil can begenerally shaped as a blade or thin solenoid, which receives powerinductively, which is then used to power or charge one or moreelectronic devices. Applications include inductive or magnetic chargingand power, and particularly usage in mobile, electronic, electric,lighting, or other devices, batteries, power tools, kitchen, industrial,medical or dental, or military applications, vehicles, robots, trains,and other usages.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a system for wireless powering or charging ofdevices, in accordance with an embodiment.

FIG. 2 illustrates another view of a wireless charger system, inaccordance with an embodiment.

FIG. 3 illustrates an example of a charger coil, in accordance with anembodiment.

FIG. 4 illustrates a resulting magnetic field, in accordance with anembodiment.

FIG. 5 illustrates a charger geometry, in accordance with an embodiment.

FIG. 6 illustrates a return magnetic flux from a charger, in accordancewith an embodiment.

FIG. 7 illustrates wire wrapped around a core to create a solenoid typereceiver, in accordance with an embodiment.

FIG. 8 illustrates a ferrite lower magnetic shield or flux guide, inaccordance with an embodiment.

FIG. 9 illustrates a receiver coil wrapped around a very thin magneticmaterial, in accordance with an embodiment.

FIG. 10 illustrates the use of additional magnetic or ferrite materialor layers added to or otherwise integrated with the top and/or bottom ofthe receiver coil, in accordance with an embodiment.

FIG. 11 illustrates the use of additional magnetic or ferrite materialor layers added to or otherwise integrated with the top and/or bottom ofthe receiver coil, in accordance with another embodiment.

FIG. 12 illustrates integration of a receiver into a wearable headset orelectronic display device or glasses, in accordance with an embodiment.

FIG. 13 illustrates an embodiment that incorporates magnetic or ferritematerial sections above and below the main coil section, in accordancewith an embodiment.

FIG. 14 illustrates integration of a receiver into a mobile phone, inaccordance with an embodiment.

FIG. 15 illustrates that incorporates magnetic or ferrite materialsections above and below the main coil section, in accordance with anembodiment.

FIG. 16 illustrates integration of a receiver into a headset device, inaccordance with an embodiment.

FIG. 17 illustrates a charger for use in coupling to a blade typereceiver in the outer perimeter of the charger surface, in accordancewith an embodiment.

FIG. 18 illustrates a charger that provides different sections withdifferent operating principles or protocols and/or driving and/orcommunication sections, in accordance with an embodiment.

FIG. 19 illustrates a charger that provides different sections, inaccordance with another embodiment.

FIG. 20 illustrates a charger that provides different sections, inaccordance with another embodiment.

DETAILED DESCRIPTION

With the proliferation of electrical and electronic devices and vehicles(which are considered examples of devices herein), simple and universalmethods of providing power and or charging of these devices is becomingincreasingly important.

In accordance with various embodiments, the term device, product, orbattery is used herein to include any electrical, electronic, mobile,lighting, or other product, batteries, power tools, cleaning,industrial, kitchen, lighting, military, medical, dental or specializedproducts and vehicles, automobiles, personal mobility (e.g., Segwaytype) devices, buses, or movable machines such as robots or other mobilemachines or other devices whereby the product, part, or component ispowered by electricity or an internal or external battery and/or can bepowered or charged externally or internally by a generator or solarcell, fuel cell, hand or other mechanical crank or alike.

In accordance with an embodiment, a product or device can also includean attachable or integral skin, case, cover, battery door or attachableor add-on or dongle type of receiver component, to enable the user topower or charge the product, battery, or device.

Induction generally refers to generation of electromotive force (EMF) orvoltage across a closed electrical path in response to a changingmagnetic flux through any surface bounded by that path. In literature,sometimes magnetic induction is defined as if it is limited totightly-coupled cases whereby the charger and receiver coils are ofsimilar sizes or the gap between them is small. Magnetic resonance is aterm that has been used recently for inductive power transfer where thecharger and receiver may be far apart or the transmitter and receivercoils are of different size. The term loosely-coupled wireless charginghas also been used for these systems. Since magnetic resonance orloosely-coupled wireless charging is in general a form of induction, asused herein in accordance with various embodiments the term induction isused for any of these systems (including inductive or tightly-coupledwireless power transfer, magnetic resonant or loosely-coupled wirelesspower transfer and hybrid systems), and induction and magnetic resonanceare sometimes used interchangeably to indicate that the method of powertransfer can be in either domain or a combination thereof.

In accordance with various embodiments, an inductive power transmitteremploys a magnetic induction coil(s) transmitting energy to a receivingcoil(s) in or on a device or product, case, battery door, or attachableor add-on component including attachments such as a dongle or a batteryinside or outside of device or attached to device through a connectorand/or a wire, or stand-alone placed near or on the power transmitterplatform. The receiver can be an otherwise incomplete device thatreceives power wirelessly and is intended for installation or attachmentin or on the final product, battery or device to be powered or charged,or the receiver can be a complete device intended for connection to adevice, product or battery directly by a wire or wirelessly. As usedherein, the term wireless power, charger, transmitter or inductive ormagnetic resonance power and charger are used interchangeably.

In accordance with an embodiment, the wireless charger can include aflat or curved surface, or an open or enclosed volume or part that canprovide energy wirelessly to a receiver. It can also be constructed offlexible materials and/or coils or even plastic electronics to enablemechanical flexibility and bending or folding to save space or forconformity to non-flat surfaces.

In accordance with an embodiment, the wireless charger can be directlypowered by an AC power input, DC power, or other power source such as acar, motorcycle, truck or other vehicle or airplane or boat or shippower outlet, or vehicle, boat, ship or airplane itself, primary(non-rechargeable) or rechargeable battery, solar cell, fuel cell,mechanical (e.g., hand crank, wind, or water source), nuclear source, orother wireless charger or power supply or a combination thereof. Inaddition, the wireless charger can be powered by a part such as arechargeable battery which is itself in turn recharged by another sourcesuch as an AC or DC power source, vehicle, boat or ship or airplaneoutlet or vehicle, boat or ship or airplane itself, solar cell, fuelcell, mechanical (e.g., hand crank, wind, or water source) or nuclearsource, or a combination thereof.

In accordance with various embodiments, in applications where thewireless charger is powered by a rechargeable source such as a battery,the battery can also be itself in turn inductively charged by anotherwireless charger. The wireless charger can be a stand-alone part,device, or product, or can be incorporated into another electric orelectronics device, table, desk chair, armrest, TV stand or mount orfurniture or vehicle or airplane or marine vehicle or boat or objectssuch as a table, desk, chair, counter-top, shelving or check out orcashier counters, kiosk, car seat, armrest, car console, car door,netting, cup holder, dashboard, glove box, etc., airplane tray,computer, laptop, netbook, tablet, phone, display, TV, magnetic, opticalor semiconductor storage or playback device such as hard drive, solidstate storage drive, optical players, etc., cable or game console,computer pads, toys, clothing, bags, case or backpack, belt or holster,etc., industrial, medical, dental, military equipment or kitchencounter, area, devices and appliances, phones, cameras, radios, stereosystems, speakers, etc. The wireless charger can also have otherfunctions built in, or be constructed such that it is modular andadditional capabilities or functions can be added as needed.

In accordance with various embodiments, some of these capabilities orfunctions include an ability to provide higher power, charge moredevices, exchange the top surface or exterior box or cosmetics, operateby internal power as described above through use of a battery and/orrenewable source such as solar cells, communicate and/or store data froma device, provide communication between the device and other devices orthe charger and/or a network, etc. An example is a basic wirelesscharger that has the ability to be extended to include a rechargeablebattery pack to enable operation without external power. Examples ofproducts or devices powered or charged by the induction transmitter andreceiver include but are not limited to batteries, cell phones, smartphones, cordless phones, communication devices, heads-up displays,wearable computer with head mounted display, 3-d TV glasses, wearableelectronic glasses, wearable computer or communication devices,communication or display watches, pagers, personal data assistants,portable media players, global positioning (GPS) devices, poweredheadphones or noise cancelling headphones, Bluetooth headsets and otherdevices, shavers, watches, tooth brushes, calculators, cameras, opticalscopes, infrared viewers, computers, laptops, tablets, netbooks,keyboards, computer mice, book readers or email devices, pagers,computer monitors, televisions, music or movie players and recorders,storage devices, radios, clocks, speakers, gaming devices, gamecontrollers, toys, remote controllers, power tools, cash register,delivery or other type of scanners, construction tools, officeequipment, robots including vacuum cleaning robots, floor washingrobots, pool cleaning robots, gutter cleaning robots or robots used inhospital, clean room, military or industrial environments, industrialtools, mobile vacuum cleaners, medical or dental tools, medicalstretcher batteries, military equipment or tools, kitchen appliances,mixers, cookers, can openers, food or beverage heaters or coolers suchas electrically powered beverage mugs, massagers, adult toys, lights orlight fixtures, signs or displays, or advertising applications,electronic magazines or newspapers or magazines or newspapers containingan electronic and/or display part, printers, fax machines, scanners,electric vehicles, electric golf carts, buses, trains, motorcycles orbicycles, personal mobility (e.g., Segway type) devices, trains or othervehicles or mobile transportation machines, and other battery orelectrically powered devices or products or a product that is acombination of the products listed above.

In accordance with an embodiment, the receiver and/or the charger can beincorporated into a bag, carrier, skin, cover, clothing, case,packaging, product packaging or box, crate, box, display case or rack,table, bottle or device etc. to enable some function inside the bag,carrier, skin, clothing, case, packaging, product packaging or box,crate, box, display case or rack, table, bottle (such as, e.g., causinga display case or packaging to display promotional information orinstructions, or to illuminate) and/or to use the bag, carrier, skin,clothing, case, packaging, product packaging or box, crate, box, standor connector, display case or rack, table, bottle, etc., to power orcharge another device or component somewhere on or nearby.

In accordance with various embodiments, the product or device does notnecessarily have to be portable and/or contain a battery to takeadvantage of induction or wireless power transfer. For example, alighting fixture or a computer monitor that is typically powered by anAC outlet or a DC power supply can be placed on a table top and receivepower wirelessly. The wireless receiver can be a flat or curved surfaceor part that can receive energy wirelessly from a charger. The receiverand/or the charger can also be constructed of flexible materials and/orcoils or even plastic electronics to enable mechanical flexibility andbending or folding to save space or for conformity to non-flat surfaces.

In accordance with various embodiments, many of these devices containinternal batteries, and the device may or may not be operating duringreceipt of power. Depending on the degree of charge status of thebattery, or its presence and the system design, the applied power mayprovide power to the device, charge its battery or a combination of theabove. The terms charging and/or power are used interchangeably hereinto indicate that the received power can be used for either of thesecases or a combination thereof. In accordance with various embodiments,unless specifically described, these terms are therefore usedinterchangeably. Also, unless specifically described herein, inaccordance with various embodiments, the terms charger, power supply,and transmitter are used interchangeably.

FIG. 1 illustrates a system for wireless powering or charging of devicesin accordance with an embodiment. As shown in FIG. 1, in accordance withan embodiment, a wireless charger or power system 100 comprises a firstcharger or transmitter part 110, and a receiver 120 connected to amobile or stationary device, vehicle or battery or its charging or powercircuit to provide electric power to power or charge the mobile orstationary device, vehicle or its battery.

FIG. 1 shows an example where one charger or power transmitter ischarging or powering one receiver. However, in a more general case, thetransmitter may comprise one or more transmitters or chargers operatingat different power levels and/or using different protocols to power oneor more receivers operating at different power levels, voltages and/orprotocols.

FIG. 2 illustrates a more detailed view of a wireless charger system128, in accordance with an embodiment, with a resonant convertergeometry, wherein a pair of transistors Q1 and Q2 in the charger 130(such as FETs, MOSFETs, or other types of switch) are driven by ahalf-bridge driver IC and the voltage is applied to the coil L1 throughone or more capacitors shown as C1. In accordance with an embodiment,the receiver 140 includes a coil and an optional capacitor (for addedefficiency) shown as C2 that can be in series or in parallel with thereceiver coil L2. The charger and/or receiver coils can also includeimpedance matching circuits and/or appropriate magnetic material layersbehind (on the side opposite to the coil surfaces facing each other)them to increase their inductance and/or to shield the magnetic fieldleakage to surrounding area. The charger and/or receiver can alsoinclude impedance matching circuits to optimize or improve powertransfer between the charger and receiver.

In several of the embodiments and figures described herein, the resonantcapacitor C2 in the receiver is shown in a series embodiment. This isintended only as a representative illustration, and in accordance withvarious embodiments this capacitor can be used in series or parallelwith the receiver coil. Similarly, the charger is generally shown inaccordance with an embodiment where the resonant capacitor is in serieswith the coil. System implementations with the capacitor C1 in parallelwith the charger coil are also possible.

In accordance with an embodiment, the charger can also include a circuitthat measures the current through and/or voltage across the charger coil(for example, in FIG. 2, a current sensor is shown as an example).Communication between the receiver and the charger can also be providedthrough the same coils as used for the power transfer, throughmodulation of a load in the receiver. Various demodulation methods fordetection of the communication signal on the charger current or voltageare available. This demodulation mechanism can be, e.g., an AM or FMreceiver (depending on whether amplitude or frequency modulation isemployed in the receiver modulator) similar to a radio receiver tuned tothe frequency of the communication or a heterodyne detector.

In accordance with an embodiment, the communication and control betweenthe charger and the receiver(s) is conducted over a separate oradditional RF or optical or other channels. Optional methods ofcommunication between the charger and receiver can be provided throughthe same coils as used for transfer of power, through a separate coil,through an RF or optical link, through, e.g., RFID, Bluetooth, WiFi,Wireless USB, NFC, Felica, Zigbee, or Wireless Gigabit (WiGig) orthrough such protocols as defined by the Wireless Power Consortium(WPC), Alliance for Wireless Power (A4WP) or other protocols orstandards, developed for wireless power, or specialized protocols suchas Dedicated Short Range Communications (DSRC) for automotiveapplications, or other communication protocol, or combinations thereof.

In accordance with an embodiment, the microcontroller unit (MCU) in thecharger (shown as MCU1 in FIG. 2) is responsible for decoding thecommunication signal from a detection/demodulation circuit and,depending on the algorithm used, making appropriate adjustments to thecharger coil drive circuitry to achieve the desired output voltage,current or power from the receiver output.

In accordance with various embodiments, it may be preferable for one ormore receivers to receive power when placed at a variety of locations oranywhere on or near a wireless charger area. Such an implementation, ingeneral would benefit from a charger and/or receiver design that allowsa uniform power transfer over an area or the entire surface of thecharger. To provide more uniform power transfer across a coil, inaccordance with an embodiment, methods to provide a more uniformmagnetic field across a coil can be used. For example, one method forachieving this uses a hybrid coil comprising a combination of a wire andPCB coils (e.g., X. Liu and S. Y. R. Hui, “Optimal design of a hybridwinding structure for planar contactless battery charging platform,”IEEE Transactions on Power Electronics, vol. 23, no. 1, pp. 455-463,2008). In another method, the transmitter coil can be constructed ofLitz wire or patterned printed circuit board (PCB) and has a patternthat is very wide between successive turns at the center and is moretightly wound as one gets closer to the edges (e.g., J. J. Casanova, Z.N. Low, J. Lin, and R. Tseng, “Transmitting coil achieving uniformmagnetic field distribution for planar wireless power transfer system,”in Proceedings of the IEEE Radio and Wireless Symposium, pp. 530-533,January 2009). FIG. 3 shows an example of a coil 150 in accordance withan embodiment, while FIG. 4 shows a resulting magnetic field 152.

In a geometry described in U.S. Patent Publication No. 20080067874, aplanar spiral inductor coil is demonstrated, wherein the width of theinductor's trace becomes wider as the trace spirals toward the center ofthe coil to achieve a more uniform magnetic field allowing morepositioning flexibility for a receiver across a transmitter surface.

In yet other embodiments (e.g., F. Sato, et al., IEEE Digest of Intermag1999, PP. GR09, 1999), the coil can be a meandering type of coil,wherein the wire is stretched along X or Y direction and then folds backand makes a back and forth pattern to cover the surface.

In accordance with an embodiment, the charger can operate continuously,and any appropriate receiver coil placed on or near its surface willbring it to resonance and will begin receiving power. The regulation ofpower to the output can be performed through a regulation stage and/ortuning of the resonant circuit at the receiver. Advantages of such asystem include that multiple receivers with different power needs can besimultaneously powered in this way. The receivers can also havedifferent output voltage characteristics.

In accordance with embodiments described in U.S. patent application Ser.No. 13/352,096, published as U.S. Patent Publication No. 20120235636,which application is herein incorporated by reference, two techniqueshave been described whereby through appropriate design of the system, aposition-independent power transfer system with reduced or noundesirable radiation and high efficiency can be achieved. Thesegeometries use a saturable magnetic layer placed above the charger coilarea to shield the charger magnetic layer from the surrounding area.

For example, in accordance with an embodiment, a Magnetic Aperture (MA)receiver includes an appropriate magnet in the receiver that cansaturate the shield layer nearby the receiver and allow coupling ofpower only in that area of the charger, resulting in efficient powercoupling with minimal residual electromagnetic emission from nearbyareas. In accordance with an embodiment, a Magnetic Coupling (MC) systememploys a similar geometry but uses the increase in the resonantelectromagnetic field between the charger and receiver coils toself-saturate the layer, and does not require a receiver magnet tooperate and achieve similar results. These two techniques are furtherdescribed in the patent applications referenced above.

FIG. 5 shows an additional geometry 160 whereby a charger coil 162 isplaced on a magnetic flux guide/shielding layer 164 that extends beyondthe edges of the coil. The receiver similarly has a magneticflux/shielding layer 166 that extends beyond the size of the coil 168,allowing an overlap area between these flux layers on the top and bottomsides of the receiver. FIG. 6 shows 170 the return magnetic flux fromthe charger that passes the receiver coil and is guided efficiently toclose on itself. Such an efficient flux guide (FG) geometry results inconfinement of power transfer to the area of overlap of a receiver andcharger coil, and significant increase in power transfer efficiency andreduction of undesirable electromagnetic emission compared to MagneticResonance (MR) systems. It is also possible to further decrease anypotential emissions from non-covered areas of the charger coil bycovering the charger coil with a magnetic shield layer and combining theFG geometry with the earlier described MC or MA modes of operation.

In accordance with the MC geometry, the reluctance of the flux path inthe receiver can be lowered by including high permeability material inthe core of the receiver ring coil (similar to a solenoid) or a T-shapecore or alike. Many geometries are possible, and these geometries areprovided merely as examples. Additionally, while in accordance with anembodiment a Litz wire receiver coil can be used, in accordance withother embodiments, PCB coils and/or a combination of Litz wire and PCBcoil can be used.

In accordance with an embodiment, to reduce the reluctance of the path,the receiver coil can be created by using a flux guide material (such asferrite with permeability greater than 1), with an axis perpendicular(or an angle sufficient to catch the substantially perpendicular fluxfrom the charger) to the surface of the charger. As shown 172 in FIG. 7,Litz wire can be wrapped around the core to create a solenoid typereceiver with a relatively small cross section (several mm or smaller by10 or 20 mm) substantially parallel to the surface of the charger. Inone example, the solenoid height (along the direction of axis of wirewrapped around it, and perpendicular to the surface of the charger) canbe varied from 10 to 20 mm, but can be shorter. A typical number ofturns on the receiver coil can be 7 to 20 turns. Use of a series orparallel capacitor with such a receiver coil provides a resonant circuitwhose output can be rectified and smoothed with a capacitor to provide aDC output. To provide regulated power output, as shown in FIGS. 1 and 2,a communication or feedback system between charger and receiver and/oran output stage regulator can also be added.

In one example, a charger coil similar to that shown in FIG. 3 and witha thin (0.5 mm thick) ferrite lower magnetic shield/flux guide similarto that shown 174 in FIG. 8 was used. Substantial power transfer (over20 W) and high efficiencies of up to 55% DC to DC (DC power output ofreceiver rectifier divided by input to DC charger circuit input power)was received over the entire surface of the charger coil when thecharger coil and its associated resonant capacitor were tuned to beresonant at similar frequencies to the receiver coil and its associatedcapacitor. Power was received with the receiver coil having zero up toseveral cm of gap from the surface of the charger coil. Such a smallsolenoid can be provided having very small sizes in one or twodimensions, such that it is shaped as or otherwise resembles a blade,with the contact area being the thin edge of the blade.

In accordance with an embodiment, rotating the angle of the bladesolenoid with respect to the perpendicular direction to the surface tothe charger can produce large power transfers, confirming that as longas some component of the charger flux is along the axis of the receivercoil, efficient power transfer can be obtained. Both position-free andmultiple receiver operation can be provided. As shown in FIG. 7,optionally, an additional magnetic shield/guide layer on the top of thereceiver and/or on the bottom of the charger can also be included. Inmany applications, it is beneficial to utilize receivers that occupyminimal space and are able to fit inside (or inside an optional part of)a small mobile or fixed position device.

In accordance with an embodiment shown in FIG. 8, the charger does notutilize a top magnetic layer, and the flux guiding through the magneticcore and/or magnetic layers at the bottom of charger and/or top ofreceiver is used to provide a low reluctance path for magnetic flux flowand efficient power transfer.

Some examples of the types of devices that can include a small bladetype receiver include mobile phones, MP3 players, and wearable computerssuch as displays, communication and display watches, and electronicglasses. In some applications, the device to be charged has a smallsurface area that is in contact with the charger surface, for examplecylindrical batteries that are placed vertically to be charged, ordevices such as wearable electronic glasses or displays whereby thedevice has a small surface area when placed against a flat or curvedcharger. In accordance with an embodiment, use of the flux guide and asmaller cross-section parallel to the surface of the charger, as shownin FIG. 7 or 8, may be useful for these types of applications.

In accordance with an embodiment, a receiver coil or solenoid with amagnetic flux guide can also be constructed to have a somewhat largerarea parallel to the surface of the charger, approximating theembodiment illustrated in FIG. 6, but with a flux guide layer or core inthe middle of the coil. In this case, the height of this flux guide orcore (along the length perpendicular to the surface of the charger) canbe made quite short (e.g., 1-2 mm or less).

In accordance with an embodiment, shown in FIG. 9, the receiver coil canbe wrapped around a very thin magnetic material. By way of example, inaccordance with an embodiment 180, 182 this material can be 1 mm or lessin thickness. In one example, coils comprising 0.6 mm thick Litz wire ofbundled wire can be wrapped around 0.3 mm thick sheet of 600permeability ferrite material (20×10×0.3 mm size) and used for such areceiver. Using such a blade type receiver with a coil surface area of20×0.3 mm on a charger surface of 170 mm×170 mm or larger coil withpattern similar to FIG. 3, power transfer levels exceeding 20 W, and DCto DC power transfer efficiencies of up to 55%, were observed when thereceiver coil was placed at any location and orientation (with the axisof the receiver coil having some component perpendicular to the surfaceof the charger) on or near the surface of the charger. Additionally,significant power transfer was observed when the receiver coil was movedaway from the charger coil in a vertical direction (with coil to coilspacing of 20 mm or larger). Considering that the blade type receivercoil surface occupies an area of 0.02% of the area of the charger coil,achieving such a high level of power transfer and efficiencydemonstrates that the flux generated at the surface of the charger coilis efficiently guided and channeled to the location of the receivercoil.

In accordance with an embodiment, such a coil can be made to besymmetrical along its winding axis, and can receive power when the coilis flipped vertically. Such a feature may provide additional flexibilityand usage in some applications.

In accordance with another embodiment shown 190, 192 in FIGS. 10, and202, 202 in FIG. 11, additional magnetic or ferrite material or layerscan be added to or otherwise integrated with the top and/or bottom ofthe receiver coil and its associated magnetic section. Such layers aidin the guidance of the flux generated in the receiver coil and canprovide higher efficiency and/or power.

In accordance with an embodiment, the receiver can be used to charge orpower wearable mobile communication and display devices, such aswearable electronic glasses, watches, headsets, or other devices. Anexample of an embodiment for integration into wearable headsets orelectronic display devices or glasses is shown 212 in FIG. 12. Inaccordance with an embodiment, a device such as an electronic glassescan be oriented on a surface as shown, to receive charging. Alternately,the electronic glasses can be flipped vertically so the top flat side isin contact with a charging surface. In either orientation, the surfacearea of the device in or near contact with the charger surface can bequite small.

FIG. 12 shows an embodiment that incorporates the receiver coil and/orits associated electronics in a section with a small horizontal (in theplane of the charger coil if the device is laid down on a chargersurface) surface area. The embodiments of the receiver coil describedabove are useful for this implementation, and can also be incorporatedin another embodiment 214 shown in FIG. 13 that incorporates magnetic orferrite material sections above and below the main coil section tofurther guide the magnetic flux. These layers can also be used to guideor route the charger magnetic flux around the inside cavity and shieldany PCB, circuit, battery, or metallic part that may be included in thisspace from the magnetic field of the charger.

Since, in accordance with an embodiment, such a receiver can besymmetrical in the Z axis (perpendicular to surface of charger or alongthe axis of the receiver coil winding), the electronic glasses can belaid down in any of the several orientations flatly on the surface andpower will be received by the receiver. In addition, the X and Yposition freedom created by the charger coil allows the user to placethe electronic glasses at any location on the charger, and even at a Zdistance, to receive power.

In accordance with an exemplary embodiment, when a receiver withintegrated horizontal flux guide sections, such as the embodiment shownin FIG. 11, was placed near the outer areas of a 170 mm×170 mm chargercoil such as that shown in FIG. 8, with a charger under a layer offerrite material flux guide, it was observed that the receiver canreceive power even when its coil axis is parallel to the chargersurface. This is due to the large parallel (to the surface) component ofthe charger magnetic flux in these outer areas. The smaller horizontalsections in the receiver coil (shown as the end flux guides in FIG. 11)also aid in guiding the flux into and out of the receiver coil, andenable operation of the receiver in any orientation. This behaviorenables a receiver such as that shown in FIG. 11 to be generallyrotatable at any angle along an axis perpendicular to the plane of theorientation shown in lower part of FIG. 11, when placed on a charger,and still receive power. This behavior can be useful for thoseapplications where orientation independence is required.

In accordance with another embodiment, the receiver can be integratedinto devices such as mobile phones, MP3 players, tablets, watches,batteries, headsets, or other devices where limited space is available.FIG. 14 shows an embodiment 220 for integration into a mobile phone atan edge of the phone, or somewhere within the body of the phone. Such aphone with the receiver integrated can be charged when placed at anylocation on a charger surface. In accordance with another embodiment222, horizontal magnetic or ferrite layers on top and bottom can beused, as shown in FIG. 15.

As described above, in accordance with an embodiment, the receiver coilcan be made to be symmetrical along its winding axis, which enables, ineither of the embodiments, the phone or other electronic device to becharged with either its back side or its front facing the chargersurface. In accordance with an embodiment, the charger and/or thereceiver can also be configured to detect the orientation or front-backplacement of the device during charging and perform additionalfunctionalities. For example, a phone can be configured so that when thephone is placed face-down on the charger, it can be charged but willenter a “Do Not Disturb” mode so that any incoming calls, messages,texts, emails, etc., will not provide audio, visual or otherindications; but, when placed on the charger in its other orientation(display face-up), incoming information can be relayed to the uservisually, by audio or even displayed or transmitted to another device(such as transmission to another display when used in cars).

The above illustration is an example of a contextually-aware operation;in accordance with various embodiments, such activities of tyingwireless charging to, e.g., launching or performance of other activitiesor commands can be considered examples of contextually aware charging,additional examples of which are described in U.S. Patent PublicationNo. 20110050164, which examples can be combined or used with variousembodiments of the charger and receiver technologies described herein.

FIG. 16 shows another embodiment 224 for integration of a sheet or bladetype receiver coil within an electronic device, in this illustration aheadset device, e.g., at the edge or back of the headset, or anothersuitable location within the body of the headset.

Charger and Receiver Interaction

In accordance with an embodiment, the receiver can be provided as anintegral part of a device or battery as described above, or can beprovided as an otherwise incomplete device that receives powerwirelessly and is intended for installation or attachment in or on thefinal product, battery or device to be powered or charged, or thereceiver can be a complete device intended for connection to a device,product or battery directly by a wire or wirelessly. Examples includereplaceable covers, skins, cases, doors, jackets, surfaces, etc fordevices or batteries that would incorporate the receiver or part of thereceiver and the received power would be directed to the device throughconnectors in or on the device or battery or the normal wired connector(or power jack) of the device or battery. The receiver can also be apart or device similar to a dongle or insert etc., that can receivepower on or near the vicinity of a charger and direct the power to adevice or battery to be charged or powered through a wire and/orappropriate connector. Such a receiver can also have a form factor thatwould allow it to be attached in an inconspicuous manner to the device,such as a part that is attached to the outer surface at the bottom,front, side, or back side of a laptop, netbook, tablet, phone, gameplayer, camera, headset or other electronic device, and routes thereceived power to the input power connector, battery connector or jackof the device.

In accordance with an embodiment, the connector of such a receiver canbe configured such that it has a pass-through or a separate connectorintegrated into it, so that a wire cable for providing wired charging orpower or communication can be connected to the connector without removalof the connector, thus allowing the receiver and its connector to bepermanently or semi-permanently be attached to the device throughout itsoperation and use.

In a more integrated approach, the coil, shield and/or the receivercircuit can be integrated into the construction of the electric orelectronic device, and be an integral part of the operation of thedevice which is powered or charged primarily or as an option (inaddition to wired charging) through the wireless power received from thereceiver. Many other variations of the receiver implementation arepossible, and these examples are not meant to be exhaustive.

In accordance with an embodiment, the receiver can also be provided as awhole or as a part of the electronics, coil, shield, or other part ofthe system required for receiving power wirelessly. The electronics cancomprise discrete components or microcontrollers that when used togetherprovide the wireless receiver functionality, or comprise an ApplicationSpecific Integrated Circuit (ASIC) chip or chipset or MCM that isspecifically configured to function as the whole or a substantial partof the electronics for wireless receiver system.

In accordance with an embodiment, a system with largely mis-matched(i.e. dissimilar in size or shape) charger and receiver coils canpotentially have several advantages. For example, power can betransferred to the receiver coils placed anywhere on the transmittercoil. Several receivers can be placed and powered on one transmitterallowing for simpler and lower cost of transmitter. The system withhigher resonance Q can be configured so the gap between the transmitterand receiver coil can be larger than a tightly-coupled system leading todesign of systems with more design freedom. In practice, power transferin distances of several cm or even higher have been demonstrated. Powercan be transferred to multiple receivers simultaneously. In addition,the receivers can potentially be of differing power rating or be indifferent stages of charging or require different power levels and/orvoltages.

In accordance with an embodiment, in order to achieve the abovecharacteristics and to achieve high power transfer efficiency, the lowerk value is compensated by using a higher Q through design of lowerresistance coils, etc. The power transfer characteristics of thesesystems may differ from tightly-coupled systems and other power drivegeometries such as use of resonant converters. Class E amplifiers orZero Voltage Switching (ZVS) or Zero Current Switching (ZCS) or otherpower transfer systems may potentially operate more efficiently in thesesituations. In addition, impedance matching circuits at the chargertransmitter and/or receiver may be required to enable these systems toprovide power over a range of load values and output current conditions.General operation of the systems can, however be quite similar to thetightly-coupled systems and one or more capacitors in series or parallelwith the transmitter and/or receiver coils is used to create a tunedcircuit that may have a resonance for power transfer. Operating nearthis resonance point, efficient power transfer across from thetransmitter to the receiver coil can be achieved. Depending on the sizedifference between the coils and operating points, efficiencies of over50% up to near 80% have been reported in such loosely-coupled systems.

To provide communication and control between the charger and receiver orreceivers, in accordance with an embodiment, a hardware PhysicalCommunication and Control Layer (PCCL) and a software or firmwareCommand and Control Layer (CCL) can be implemented. Optional methods ofcommunication between the charger and receiver(s) can be providedthrough the same coils as used for transfer of power, through a separatecoil, through an RF or optical link, through RFID, Bluetooth, Wi-Fi,Wireless USB, NFC, Felica, Zigbee, Wireless Gigabit (WiGig), 3G, 4G,etc. or through such protocols as defined by the Wireless PowerConsortium (WPC), Alliance for Wireless Power (A4WP), or Power MattersAlliance (PMA), or other protocols such as Dedicated Short RangeCommunication (DSRC) used for automotive applications or otherstandards, developed for wireless power, or other communicationprotocol, or combination thereof.

In simpler architectures, there may be minimal or no communicationbetween the charger and receiver. For example, a charger can beconfigured to be in a standby power transmitting state, and any receiverin close proximity to it can receive power from the charger. Thevoltage, power, or current requirements of the device or batteryconnected to the receiver circuit can be unregulated, or regulated orcontrolled completely at the receiver or by the device attached to it.In this instance, no regulation or feedback or communication between thecharger and receiver may be necessary. In a variation of this, thecharger can be configured to be in a state where a receiver in closeproximity would bring it into a state of power transmission. Examples ofthis would be a resonant system where inductive and/or capacitivecomponents are used, so that when a receiver of appropriate design is inproximity to a charger, power is transmitted from the charger to areceiver; but without the presence of a receiver, minimal or no power istransmitted from the charger.

In accordance with an embodiment, in those examples in whichcommunication is provided through the power transfer coils, one methodfor communication from receiver or receivers to the charger is tomodulate a load or impedance in the receiver to affect the voltageand/or current in the receiver coils and therefore create a modulationin the charger coil voltage or current parameters that can be detectedthrough monitoring of its voltage or current. Other methods can includefrequency modulation, by combining the received frequency with a localoscillator signal or inductive, capacitive, or resistive modulation ofthe output of the receiver coil. In addition to communication fromreceivers to a charger transmitter, it is also possible to modulate thecharger voltage at a pre-determined frequency and communication protocoland detect at each receiver to provide communication from the charger tothe receivers. Such bi-directional communication may be advantageous incases where the charger is used to power multiple receivers as will beexplained later.

In accordance with an embodiment, the communicated information from areceiver to the charger transmitter can be the output voltage, current,power, device or battery status, validation ID for receiver, end ofcharge or various charge status information, receiver battery, device,or coil temperature, and/or user data such as music, email, voice,photos or video, or other form of digital or analog data used in adevice. It can also be patterns or signals or changes in the circuitconditions that are transmitted or occur to simply notify the presenceof the receiver nearby.

In accordance with an embodiment, the data communicated can be any oneor more of the information detailed herein, or the difference betweenthese values and the desired value, or simple commands to increase ordecrease power, or simply one or more signals that would confirmpresence of a receiver or a combination of the above. The receiverand/or charger and/or their coils can also include elements such asthermistors, magnetic shields or magnetic cores, magnetic sensors, andinput voltage filters, etc., for safety and/or emission compliancereasons. The receiver can also be combined with other communication orstorage functions, such as NFC, Wi-Fi, Bluetooth, etc. In addition, thecharger and or receiver can include means to provide more precisealignment between the charger and receiver coils or antennas. These caninclude visual, physical, or magnetic means to assist the user inalignment of parts. To implement more positioning freedom of thereceiver on the charger, the size of the coils can also be mismatched.For example, the charger can comprise a larger coil size, and thereceiver a smaller one, or vice versa, so that the coils do not have tobe precisely aligned for power transfer.

In accordance with an embodiment, to minimize stand-by power use, thecharger can periodically be turned on to be driven with a periodicpattern (a ping process) and if a receiver in proximity begins to drawpower from it, the charger can detect power being drawn from it and stayin a transmitting state. If no power is drawn during the ping process,the charger can be turned off or placed in a stand-by or hibernationmode to conserve power, and turned on and off again periodically tocontinue seeking a receiver.

In accordance with an embodiment, the charger also includes a circuitthat measures the current through and/or voltage across the charger coil(for example, a current sensor is shown in FIG. 2 by way of example). Asdescribed earlier, various demodulation methods for detection of thecommunication signal on the charger current or voltage can be used.

While a system for communication between the charger and receiverthrough the power transfer coils or antennas is described above, inaccordance with an embodiment the communication can also be implementedthrough separate coil or coils, a radio frequency link (AM, FM or othercommunication method), an optical communication system, or a combinationof the above. The communication in any of these methods can also bebi-directional rather than uni-directional as described above.

In accordance with another embodiment, a dedicated RF channel foruni-directional or bi-directional communication between the charger andreceiver can be implemented for validation and/or regulation purposes.This system can be similar to the system shown in FIG. 2, except ratherthan load modulation being the method of communication, themicrocontroller (MCU) in the receiver transmits the required informationover an RF communication path. A similar system with LED or lasertransceivers or detectors and light sources can be implemented.Advantages of such a system include that the power received is notmodulated and therefore not wasted during communication and/or that nonoise due to the modulation is added to the system.

In accordance with an embodiment, the microcontroller unit (MCU) in thecharger (MCU1) is responsible for recognizing and understanding thecommunication signal from the detection/demodulation circuit and,depending on the algorithm used, making appropriate adjustments to thecharger coil drive circuitry to achieve the desired output voltage,current or power from the receiver output. In addition, MCU1 isresponsible for processes such as periodic start of the charger to seeka receiver at the start of charge, keeping the charger on when areceiver is found and accepted as a valid receiver, continuing to applypower and making appropriate adjustments, and/or monitoring temperatureor other environmental factors, providing audio or visual indications tothe user on the status of charging or power process, etc., orterminating charging or application of power due to end of charge, orcustomer preference, or over temperature, over current, over voltage, orsome other fault condition or to launch or start another program orprocess.

In accordance with an embodiment, once the charger MCU1 has received asignal and decoded it, it can take action to provide more or less powerto the charger coil. This can be accomplished through known methods ofadjusting the frequency, duty cycle or input voltage to the charger coilor a combination of these approaches. Depending on the system and thecircuit used, the MCU1 can directly adjust the bridge driver, or anadditional circuit such as a frequency oscillator can be used to drivethe bridge driver or the FETs. A typical circuit for the receiver, inaccordance with a load modulation communication system embodiment, isshown in FIG. 2.

In accordance with an embodiment, the receiver circuit can include anoptional capacitor C2 in parallel or series with the receiver coil toproduce a tuned receiver circuit. This circuit is known to increase theefficiency of a wireless power system. The rectified and smoothed(through rectifiers and capacitors) output of the receiver coil andoptional capacitor is either directly or through a switch or regulatorapplied to the output. A microcontroller MCU2 is used to measure variousvalues such as voltage V₁, current, temperature, state of charge,battery full status, end of charge, etc. and to report back to thecharger to provide a closed loop system with the charger as describedabove. In the circuit shown in FIG. 2, the receiver MCU2 communicatesback to the charger by modulating the receiver load by rapidly closingand opening a switch in series with a modulation load or impedance at apre-determined speed and coding pattern. This rapid load modulationtechnique at a frequency distinct from the power transfer frequency canbe easily detected by the charger. A capacitor and/or inductor can alsobe used as the modulation load.

In accordance with other embodiments, other methods of communicationthrough varying the reactive component of the impedance can also beused. The modulation scheme shown in FIG. 2 is shown only as arepresentative method and is not meant to be exhaustive. As an example,the modulation can be achieved capacitively, by replacing the resistorwith a capacitor. In this instance, the modulation by the switch in thereceiver provides an advantage that by choosing the modulation frequencyappropriately, it is possible to achieve modulation and signalcommunication with the charger coil and circuitry, with minimal powerloss (compared to the resistive load modulation).

The receiver in FIG. 2 also shows an optional DC regulator that is usedto provide constant stable voltage to the receiver MCU2. This voltagesupply may be necessary to avoid drop out of the receiver MCU2 duringstartup conditions where the power is varying largely or during changesin output current, and also to enable the MCU2 to have a stable voltagereference source so it can measure the V₁ voltage accurately.Alternatively, a switch to connect or disconnect the load can be used orcombined with the regulator. To avoid voltage overshoots duringplacement of a receiver on a charger or rapid changes in load condition,a voltage limiter circuit or elements like Transit Voltage Suppressor(TVS), Zener diodes or regulators or other voltage limiters can also beincluded in the receiver.

In the above description, a uni-directional communication (from thereceiver to the charger) is described. However, this communication canalso be bi-directional, and data can be transferred from the charger tothe receiver through modulation of the voltage or current in the chargercoil and read back by the microcontroller in the receiver detecting achange in the voltage or current, etc.

In accordance with an embodiment, the communication between the receiverand charger needs to follow a pre-determined protocol, baud rate,modulation depth, etc. and a pre-determined method for hand-shake,establishment of communication, and signaling, etc., as well asoptionally methods for providing closed loop control and regulation ofpower, voltage, etc., in the receiver.

In accordance with an embodiment, a typical wireless power system can beas follows: the charger periodically activates the charger coil driverand powers the charger coil with a drive signal of appropriatefrequency. During this ‘ping’ process, if a receiver coil is placed onor close to the charger coil, power is received through the receivercoil and the receiver circuit is energized. The receiver microcontrolleris activated by the received power and begins to perform an initiationprocess whereby the receiver ID, its presence, power or voltagerequirements, receiver or battery temperature or state of charge,manufacturer or serial number and/or other information is sent back tothe charger. If this information is verified and found to be valid, thenthe charger proceeds to provide continuous power to the receiver. Thereceiver can alternately send an end of charge, over-temperature,battery full, or other messages that will be handled appropriately bythe charger and actions performed. The length of the ping process shouldbe configured to be of sufficient length for the receiver to power upits microcontroller and to respond back and for the response to bereceived and understood and acted upon. The length of time between thepings can be determined by the implementation designer. If the pingprocess is performed often, the stand-by power use of the charger ishigher. Alternately, if the ping is performed infrequently, the systemwill have a delay before the charger discovers a receiver nearby; so inpractice, a balance may be suitable.

Alternatively, in accordance with an embodiment, the ping operation canbe initiated upon discovery of a nearby receiver by other means. Thisprovides a very low stand-by power use by the charger and can beperformed by including a magnet in the receiver and a magnet sensor inthe charger or through optical, capacitive, weight, NFC or Bluetooth,RFID or other RF communication or other methods for detection.

Alternatively, in accordance with an embodiment, the system can beconfigured or implemented to be always ON (i.e., the charger coil ispowered at an appropriate drive frequency) or pinged periodically andpresence of the receiver coil brings the coil to resonance with thereceiver coil and power transfer occurs. The receiver in this instancemay not even contain a microcontroller and act autonomously and maysimply have a regulator in the receiver to provide regulated outputpower to a device, its skin, case, or battery. In those embodiments inwhich periodic pinging is performed, the presence of a receiver can bedetected by measuring a higher degree of current flow or power transferor other means, and the charger can simply be kept on to continuetransfer of power until either the power drawn falls below a certainlevel or an end of charge and/or no device present is detected.

In another embodiment, the charger can be in an OFF or standby, or lowor no power condition, until a receiver is detected by means of itspresence through a magnetic, RF, optical, capacitive or other methods.For example, in accordance with an embodiment the receiver can containan RFID chip and once it is present on or nearby the charger, thecharger can turn on or begin pinging to detect a receiver.

In accordance with an embodiment, the protocol used for communicationcan be any of, e.g., common RZ, NRZ, Manchester code, etc., used forcommunication. As described above, the charger can periodically startand apply a ping voltage of pre-determined frequency and length to thecharger coil. The receiver is then activated, and can begin to send backcommunication signals. The communication signal can include an optionalpreamble that is used to synchronize the detection circuit in thecharger and prepare it for detection of communication. A communicationcontaining a data packet may then follow, optionally followed bychecksum and parity bits, etc. Similar processes are used incommunication systems and similar techniques can be followed. Inaccordance with an embodiment, the actual data packet can includeinformation such as an ID code for the receiver, a manufacturer's code,received voltage, power, or current values, status of the battery,amount of power in the battery, battery or circuit temperature, end ofcharge or battery full signals, presence of external wired charger, or anumber of the above. Also this packet may include the actual voltage,power, current, etc. value or the difference between the actual valueand the desired value or some encoded value that will be useful for thecharger to determine how best to regulate the output.

Alternatively, in accordance with an embodiment, the communicationsignal can be a pre-determined pattern that is repetitive and simplylets the charger know that a receiver is present and/or that thereceiver is a valid device within the power range of the charger, etc.Any combination of systems can be configured to provide the requiredperformance.

In accordance with an embodiment, in response to the receiver providinginformation regarding output power or voltage, etc., the charger canmodify voltage, frequency, duty cycle of the charger coil signal or acombination of the above. The charger can also use other techniques tomodify the power out of the charger coil and to adjust the receivedpower. Alternatively the charger can simply continue to provide power tothe receiver if an approved receiver is detected and continues to bepresent. The charger can also monitor the current into the charger coiland/or its temperature to ensure that no extra-ordinary fault conditionsexist. One example of this type of fault may be if instead of areceiver, a metal object is placed on the charger.

In accordance with an embodiment, the charger can adjust one or moreparameters to increase or decrease the power or voltage in the receiver,and then wait for the receiver to provide further information beforechanging a parameter again, or it can use more sophisticatedProportional Integral Derivative (PID) or other control mechanism forclosing the loop with the receiver and achieving output power control.Alternatively, as described above, the charger can provide a constantoutput power, and the receiver can regulate the power through aregulator or a charger IC or a combination of these to provide therequired power to a device or battery.

Various manufacturers may use different encodings, and also bit ratesand protocols. The control process used by different manufacturers orprotocols may also differ, further causing interoperability problemsbetween various chargers and receivers. A source of interoperabilitydifferences may be the size, shape, and number of turns used for thepower transfer coils. Furthermore, depending on the input voltage used,the design of a wireless power system may step up or down the voltage inthe receiver depending on the voltage required by a device by havingappropriate number of turns in the charger and receiver coils. However,a receiver from one manufacturer may then not be able to operate onanother manufacturer charger due to these differences in designsemployed.

In accordance with an embodiment, it is therefore beneficial to providea system that can operate with different receivers or chargers and canbe universal. Recently, there has been some movement to standardize thefrequency of operation, the coil and electronics characteristics, theidentification and communication method, messaging and protocol andother aspects of the systems to allow interoperability between systemsfrom different manufacturers. Several interoperability Standards andSpecifications in this area have been established or underconsideration. These include the WPC interoperability specification, theConsumer Electronics Association Standard for wireless power, theAlliance for Wireless Power (A4WP), Power Matters Alliance (PMA), theConsumer Electronics Association (CEA) Wireless Power Standards workinggroup and Wireless Power Standards for Electric Vehicle charging, andother international efforts for Specification and Standards development.

The resonant frequency, F of any LC circuit is given by:

F=½π√LC

Where L is the Inductance of the circuit or coil in Henry and C is theCapacitance in Farads.

For example, in the system shown in FIG. 3, one may use the values of C1and L1 in the above calculation for a free running charger and, as areceiver is brought close to this circuit, this value is changed by themutual coupling of the coils involved. In the example that a ferriteshield layer is used behind a coil in the charger and/or receiver, theinductance of the coil is affected by the permeability of the shield andthis modified permeability should be used in the above calculation.

In accordance with an embodiment, to be able to detect and power orcharge various receivers, the charger can be configured such that theinitial ping signal is at such a frequency range to initially be able topower and activate the receiver circuitry in any receiver during theping process. After this initial power up of the receiver, the chargercommunication circuit should be able to detect and decode thecommunication signal from the receiver. Many microcontrollers are ableto communicate in multiple formats and/or may have different input N Dconverter pins that can be configured differently to simultaneouslyreceive the communication signal and synchronize and understand thecommunication at different baud rates and protocols. In accordance withan embodiment, the charger firmware can then decide on which type ofreceiver is present and proceed to regulate or implement what isrequired (end of charge, shut-off, fault condition, etc.). Depending onthe message received, the charger can then decide to change the chargerdriver voltage amplitude, frequency, or duty cycle, or a combination ofthese or other parameters to provide the appropriate regulated output atthe receiver output.

In accordance with an embodiment, the charger's behavior can also takeinto account the difference in the coil geometry, turns ratio, etc. Forexample, a charger and receiver pair from one or more manufacturers mayrequire operation of the charger drive voltage at 150 kHz. However, ifthe same receiver is placed on a charger from another manufacturer ordriven with different coil or input voltage combination, to achieve thesame output power, the charger frequency may need to be 200 kHz. Thecharger program may detect the type of receiver placed on it and shiftthe frequency appropriately to achieve a baseline output power andcontinue regulating from there. In accordance with an embodiment, thecharger can be implemented so that it is able to decode and implementmultiple communication and regulation protocols and respond to themappropriately. This enables the charger to be provided as part of amulti-protocol system, and to operate with different types of receivers,technologies and manufacturers.

Similar techniques can be used to allow a receiver to be chargeable onchargers utilizing different protocols for communication and control.For example, the receiver may recognize the type of charger being usedby deciphering the frequency of the charger operation or its ping(through frequency filtering or other techniques) and communicate usingdifferent protocols and communication signals accordingly.

In accordance with an embodiment, for receivers that contain an onboardoutput stage regulator before the output power, stability of the inputvoltage to the regulator is not as critical since the regulator performsa smoothing function and keeps the output voltage at the desired levelwith any output load changes (such as during battery charging). Theoutput of the regulator is then directed to circuitry such as a powermanagement IC (PMIC), or to a battery for charging, or directlyconnected to the device for use in instances where the receiver acts asa power supply to a device without internal batteries, or a combinationof the above. Where an output regulator stage is used in a receiver itis critical for the wireless receiver not to exceed the maximum ratedinput voltage of the output stage regulator or to drop below a levelrequired so that the output voltage from the regulator could no longerbe maintained at the required value. Various types of output stageregulator such as buck, boost, buck-boost, linear etc., can be used asthis output stage. However, in general, inclusion of a regulator and/ora charger IC or PMIC chip (for batteries) relaxes the power/voltageregulation requirements of the wireless power receiver portion of thecircuit at the expense of the additional size and cost of thiscomponent. In accordance with some embodiments, simpler voltage limitingoutput stages such as Zener diodes, TVS or other voltage limiting orclamping ICs or circuits, can be used.

In accordance with another embodiment, the receiver can also includevariable or switchable reactive components (capacitors and/or inductors)that would allow the receiver to change its resonant condition to affectthe amount of power delivered to the device, load or battery. Thereceiver and/or charger and/or their coils can also include elementssuch as thermistors, magnetic shields or magnetic cores, magneticsensors, and input voltage filters, for safety and/or emissioncompliance reasons.

In accordance with an embodiment, the systems described herein can usediscrete electronics components or some or all of the functionsdescribed above can be integrated into an Application SpecificIntegrated Circuit (ASIC) or MCMs to achieve smaller footprint, betterperformance, noise, etc. and/or cost advantages. Such integration iscommon in the electronics industry and can provide additional advantageshere.

While the system above describes a system wherein the communication isprimarily through the coil, as described earlier, communication can alsobe implemented through a separate coil, RF, optical system or acombination of the above. In such circumstances, a multi-protocol systemcan also be used to interoperate between systems with differentcommunication and/or control protocols or even means of communication.

Flexible Systems with Multiple Protocols and Technologies

In accordance with an embodiment, a receiver or receivers placed on ornear a charger can communicate with the charger in a variety ofcommunication protocols according to different wireless chargingstandards, protocols or different proprietary methods. To distinguishthem and provide for efficient operation, the charger can be programmedto recognize different messages received, and operate differently.

For example, different protocols exist for communication and control forcharging a single receiver placed on a charger. Some systems may requirethe charger to control the voltage output from the receiver coil (thatis rectified and sent to an output of the system or to a regulator)within a tight tolerance, and cannot tolerate a large range. An exampleof such a protocol or standard is the Wireless Power Consortium (WPC) orChi, A4WP, PMA or other standard which is designed to provide tightreceiver coil output voltage tolerances and also requires chargerfrequency range of 110 to 205 kHz or higher. In accordance with anembodiment a charger system can be configured so that it recognizes sucha receiver and controls the output to within its target range. However,in other instances receivers may be designed as described above that cantolerate a larger V₁ range by using an output receiver regulator stageto allow multi-receiver charging.

In accordance with an embodiment, to address these use cases, thecharger hardware, firmware or software can be configured to recognizethe presence of such receivers and operate using a different algorithmto keep one or several receiver voltage ranges to within a largeracceptable range, and provide multi-receiver charging capability. Thisallows one charger to be interoperable with two or more protocols andsystems.

In accordance with an embodiment, the charger systems or protocols canemploy different power transfer and/or communication frequencies, ordifferent communication methods (e.g., in-band through coil, and out ofband through Wi-Fi or Bluetooth or proprietary systems) to communicateand also transfer power to receivers utilizing different protocols. Theapproaches described herein can be used to enable interoperabilitybetween such systems.

In accordance with an embodiment, the charger can use one or moredriving circuits, communication methods or protocols and/or chargerpower or communication coils or antennas to simultaneously powerdifferent receiver coils utilizing different protocols, standards and/orpower levels or voltages.

In accordance with an embodiment, the charger coil and resonantcapacitor are tuned to provide the operating frequency of the charger,and the associated receiver and its resonant capacitor is similarlytuned to the vicinity of the same frequency for optimal power transfer.It is possible to provide and control power to two or more receiverssimultaneously with one or more charger coils, by multiplexing the powertransfer frequency.

In accordance with another embodiment, the charger can contain severalresonant capacitors, such as C1 illustrated in FIG. 2, which can beswitched to form resonances with the charger coil L1, and to providecharger resonances at different frequencies. For example, depending onthe protocol of the receiver, the charger can be configured to switch touse a different C1 in series with its coil to optimize power transfer atthe preferred operating frequency of receivers from different protocols.

In accordance with an embodiment, the charger can first use one C1 valueand perform a ping operation to discover receivers adhering to afrequency of operation with that capacitor value and with theappropriate communication protocol. If an appropriate receiver isdiscovered, it can continue to provide power at that frequency andprotocol. If no such receiver is found, it can switch to use a differentvalue of C1, and repeat the ping and rotate between different C1 valuesand ping frequencies until appropriate receiver or receivers arediscovered. An advantage of using several capacitors and switchingbetween them for different protocols and/or operating frequencies isthat higher power transfer efficiencies and/or communication may beobtained compared to using a fixed C1 value.

Multi-Device Charging

FIG. 17 illustrates a charger 230 for use in coupling to a blade typereceiver in the outer perimeter of the charger surface, which can beused to power a device or receiver having a geometry similar to thatshown in FIG. 7 or 8, in this example an electronic glasses device 232.

In accordance with an embodiment, the system allows mixing or combiningof different technologies on the same charger and/or receiver, ordifferent locations or areas of the same charger. As an illustrativeexample, it may be desirable to charge two types of devicesimultaneously with different characteristics. For example, FIG. 18 andFIG. 19 show embodiments 240, 250 wherein the charger includes a largemagnetic/ferrite layer below. A plurality (e.g., two or more) separatecoil structures are used on top of the magnetic layer in the charger toprovide, in this example, two or more different sections (areas) withdifferent operating principles or protocols and/or driving and/orcommunication sections.

In the example shown in FIG. 18, the central portion can use one centralcoil to create a flux guide charge section, as described above inaccordance with the embodiment in FIG. 5. In conjunction with anappropriate flux guide type of receiver coil, this can provideposition-independent charging or power transfer in this central section.In addition, as further shown in FIG. 18, another larger coil area canbe integrated into the charger and used to create a larger charger areato be used with a receiver similar to the solenoid or blade typereceiver coils described above.

In accordance with an embodiment, since the operating frequency of eachcoil is defined by its inductance and associated resonant capacitor, theembodiments of the system shown in FIGS. 18 and 19 can be provided sothat the two coils operate either in similar, or in completelydifferent, frequency range (frequency multiplexing) to power anyassociated receivers. In accordance with an embodiment, each coil can bedriven by a separate driver circuit and communicate with the associatedreceivers using load modulation, RF or optical communication channels orcombination thereof as described earlier, and can be completelyindependent.

In accordance with another embodiment 260 shown in FIG. 20, two chargercoils for charging two different types of devices or receivers can beprovided as distinct coils that are physically separated from oneanother in space and location. For example, a charger coil can be usedto provide magnetic field and efficient coupling to a blade typereceiver in the outer perimeter of a charger surface and used to power areceiver in a geometry similar to shown in FIG. 7 or 8, while a chargeroptimized for flux guide power transfer (using a geometry such as thatshown in FIGS. 5 and 6) can be used in the center of the charger.

In accordance with an embodiment, the two coils can be distinct ordriven by different power drivers and/or use different communicationsystems and/or protocols. As an example, one of the coils and itsassociated electronics may use in-band or load modulation forcommunication and control, and the other one may use out of band or RFcommunication. The two different sections can also use different or samefrequency for power transfer as needed to optimize performance for theassociated receivers.

In accordance with an embodiment, each charger section can also chargeor power multiple receivers placed on that section. As can be seen, suchan embodiment allows the system designer to optimize the performance ofa charger to power or charge multiple device types appropriately. In theexample shown in FIG. 20, an electronic display device with a verynarrow and small receiver area can be charged position-free when it isplaced on the outer regions of the pad, while another device such as amobile phone with a receiver that may be larger (e.g., with a flat coilwith flux guide as shown on the back of the device) can be charged inthe central area of the charger. Such a combined performance charger maybe useful in various applications, and for an end-user.

The above description and embodiments are not intended to be exhaustive,and are instead intended to only show some examples of the rich andvaried products and technologies that can be envisioned and realized byvarious embodiments. It will be evident to persons skilled in the artthat these and other embodiments can be combined to produce combinationsof above techniques, to provide useful effects and products.

Some aspects of embodiments of the present invention can be convenientlyimplemented using a conventional general purpose or a specializeddigital computer, microprocessor, or electronic circuitry programmedaccording to the teachings of the present disclosure. Appropriatesoftware coding can readily be prepared by skilled programmers andcircuit designers based on the teachings of the present disclosure, aswill be apparent to those skilled in the art.

In some embodiments, the present invention includes a computer programproduct which is a storage medium (media) having instructions storedthereon which can be used to program a computer to perform any of theprocesses of the present invention. The storage medium can include, butis not limited to, any type of disk including floppy disks, opticaldiscs, DVD, CD-ROMs, microdrive, and magneto-optical disks, ROMs, RAMs,EPROMs, EEPROMs, DRAMs, VRAMs, flash memory devices, magnetic or opticalcards, nanosystems (including molecular memory ICs), or any type ofmedia or device suitable for storing instructions and/or data.

The foregoing description of the present invention has been provided forthe purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise forms disclosed.Many modifications and variations will be apparent to the practitionerskilled in the art. The embodiments were chosen and described in orderto best explain the principles of the invention and its practicalapplication, thereby enabling others skilled in the art to understandthe invention for various embodiments and with various modificationsthat are suited to the particular use contemplated. It is intended thatthe scope of the invention be defined by the following claims and theirequivalents.

What is claimed is:
 1. A system for powering or charging one or multiplereceivers or devices having small surface areas or volumes, comprising:a receiver coil generally shaped as a blade or thin solenoid, whichreceives power inductively from a charger, which is then used to poweror charge one or more electronic devices.
 2. The system of claim 1,wherein the charger includes a charger coil atop a magnetic flux guideor shielding material or layer that extends beyond the edges of thecharger coil.
 3. The system of claim 1, wherein additional magnetic orferrite material or layers are added to or otherwise integrated with thetop and/or bottom of the receiver coil, to aid in the guidance of fluxgenerated in the receiver coil.
 4. The system of claim 1, wherein thereceiver coil includes a flux guide material such as ferrite withpermeability greater than 1, with an axis perpendicular to or at anangle sufficient to receive a substantially perpendicular flux from thecharger.
 5. The system of claim 1 wherein the one or more electronicdevices is one of a portable mobile phone, music player, wearablecomputer such as a display device, communication device, watch,electronic glasses, or other mobile or electrical or electric device orvehicle.
 6. The system of claim 1, wherein the system includes a chargerhaving at least two separate coil structures provided on top of amagnetic layer to provide two or more different sections with differentoperating principles or protocols or driving and/or communicationsections, for use in powering or charging the electronic devices.
 7. Thesystem of claim 6, wherein the operating frequency of each coil isdefined by its inductance and associated resonant capacitor, so that thetwo or more coil structures operate either in similar, different,frequency ranges to power associated receivers.
 8. The system of claim1, wherein the charger is included within an automobile or othervehicle.
 9. The system of claim 1, wherein the charger and/or thereceiver can be configured to detect the orientation or front-backplacement of the device during charging and perform additionalcontextually-aware functions.
 10. The system of claim 1, wherein thecharger and the device to be powered or charged communicate to determineoptimum powering or charging.
 11. A method for powering or charging oneor multiple receivers or devices having small surface areas or volumes,comprising: a receiver coil generally shaped as a blade or thinsolenoid, which receives power inductively from a charger, which is thenused to power or charge one or more electronic devices.
 12. The methodof claim 11, wherein the charger includes a charger coil atop a magneticflux guide or shielding material or layer that extends beyond the edgesof the charger coil.
 13. The method of claim 11, wherein additionalmagnetic or ferrite material or layers are added to or otherwiseintegrated with the top and/or bottom of the receiver coil, to aid inthe guidance of flux generated in the receiver coil.
 14. The method ofclaim 11, wherein the receiver coil includes a flux guide material suchas ferrite with permeability greater than 1, with an axis perpendicularto or at an angle sufficient to receive a substantially perpendicularflux from the charger.
 15. The method of claim 11 wherein the one ormore electronic devices is one of a portable mobile phone, music player,wearable computer such as display device, communication device, watch,electronic glasses, or other mobile or electrical or electric device orvehicle.
 16. The method of claim 11, wherein the system includes acharger having at least two separate coil structures provided on top ofa magnetic layer to provide two or more different sections withdifferent operating principles or protocols or driving and/orcommunication sections, for use in powering or charging the electronicdevices.
 17. The method of claim 16, wherein the operating frequency ofeach coil is defined by its inductance and associated resonantcapacitor, so that the two or more coil structures operate either insimilar, different, frequency ranges to power associated receivers. 18.The method of claim 11, wherein the charger is included within anautomobile or other vehicle.
 19. The method of claim 11, wherein thecharger and/or the receiver can be configured to detect the orientationor front-back placement of the device during charging and performadditional contextually-aware functions.
 20. The method of claim 11,wherein the charger and the device to be powered or charged communicateto determine optimum powering or charging.